1. Field of the Invention
The present invention relates to an air intake structure for a small watercraft in which a supercharger is provided rearward of an engine so as to communicate with an intake passage via an inter-cooler. In addition, the present invention relates to a supercharger-equipped internal combustion engine for a personal watercraft.
2. Description of Background Art
Examples of an air intake structure for a small watercraft include one wherein a turbocharger (supercharger) is provided rearward of an engine and an inter-cooler is located on the side of the engine so as to communicate with the turbocharger via a communication pipe. See, JP 2004-116478.
In an air intake structure for a small watercraft, air sucked in an air cleaner is directed to the turbocharger. The air directed in the turbocharger is then directed to the inter-cooler via the communication pipe.
Thereafter, the air directed in the inter-cooler is directed to an air box via a throttle valve and then the air directed in the air box is directed in a cylinder.
The conventional air intake structure for a small watercraft includes an air box disposed on the upside of the inter-cooler. The inter-cooler and the air box are relatively largely shaped members.
In addition, it is necessary to ensure a space for disposing a cooling water hose for water-cooling and another space for arranging control harnesses around the inter-cooler.
It is difficult, therefore, to provide a relatively large shaped inter-cooler for providing an increase in capacity.
In addition, the conventional small air intake structure is such that the air outlet of a turbocharger faces upward and the air inlet of the inter-cooler faces rearwardly.
Accordingly, in order to cause the air outlet of the turbocharger to communicate with the air inlet of the inter-cooler via a communication pipe, the communication pipe needs to be bent in a complicated shape. This construction does not permit a reduction in the cost.
Commonly assigned JP 2003-27915 discloses a supercharger-equipped internal combustion engine for a personal watercraft.
The internal combustion engine for a personal watercraft disclosed in JP 2003-27915 is mounted such that a crankshaft extends in the forward and rearward direction of a watercraft body. A turbocharger or supercharger is disposed rearwardly of the engine.
In addition, a surge tank provided and projects on the side surface of the engine on the port side so as to communicate with intake ports of cylinder heads. An inter-cooler is disposed below the surge tank.
Thus, the turbocharger disposed rearwardly of the engine is spaced apart from the inter-cooler disposed on the left side of the engine, so that a long connection pipe is used to connect the turbocharger with the inter-cooler.
Such a long connection pipe interposed between the turbocharger and the inter-cooler may damage an air intake flow in a greater or less degree.
In addition, since the inter-cooler projects on the port side of a lower half portion of the engine, it is difficult to form an open space on the watercraft body.
Further, a pipe is lengthened which is adapted to introduce cooling water to the inter-cooler from the jet propulsion pipe disposed at the rear portion of the watercraft body.